The current state-of-the-art lasers for outputting high-power green light are very costly. Similarly, very high-power pulsed infrared (IR) lasers can be quite costly, making impractical their use with low-cost frequency-conversion optical devices.
U.S. patent application Ser. No. 11/484,358 titled “APPARATUS AND METHOD FOR PUMPING AND OPERATING OPTICAL PARAMETRIC OSCILLATORS USING DFB FIBER LASERS” by Angus J. Henderson is incorporated herein by reference. This application describes an optical parametric oscillator (OPO) that efficiently converts a near-infrared laser beam to tunable mid-infrared wavelength output. In some embodiments, the OPO includes an optical resonator containing a nonlinear crystal, such as periodically-poled lithium niobate. The OPO is pumped by a continuous-wave fiber-laser source having a low-power oscillator and a high-power amplifier, or using just a power oscillator. The fiber oscillator produces a single-frequency output defined by a distributed-feedback (DFB) structure of the fiber. The DFB-fiber-laser output is amplified to a pump level consistent with exceeding an oscillation threshold in the OPO in which only one of two generated waves (“signal” and “idler”) is resonant within the optical cavity. This pump source provides the capability to tune the DFB fiber laser by straining the fiber (using an attached piezoelectric element or by other means) that allows the OPO to be continuously tuned over substantial ranges, enabling rapid, wide continuous tuning of the OPO output frequency or frequencies.
U.S. patent application Ser. No. 11/017,192 titled “INJECTION SEEDED, Q-SWITCHED FIBER RING LASER” by Peter Dragic is incorporated herein by reference. This application describes a narrow linewidth, injection seeded, Q-switched Er fiber ring oscillator, that provides over 600 microWatts of average output power at 500 Hz, with 1.2 microJoules per pulse, before the output appears to be significantly affected by stimulated Brillouin scattering. This laser configuration provides multiple advantages in LIDAR systems because it offers the possibility of broad and rapid tunability.
U.S. patent application Ser. No. 10/537,900 titled “OPTICAL PULSE LASERS” by Mark Kenneth Jablonski is incorporated herein by reference. This application describes pulsed lasers which employ carbon nanotubes, particularly layers of carbon nanotubes, as saturable absorbers, mode lockers or for Q-switching elements. Also described are methods and materials for mode-locking and Q-switching of lasers in which carbon nanotubes are employed as non-linear optical materials and/or saturable absorbers which facilitate mode-locking and/or Q-switching. The invention further provides mode locker and Q-switching elements or devices which comprise one or more layers containing carbon nanotubes which layer or layers function for mode locking and/or Q-switching.
U.S. Pat. No. 6,288,835 titled “OPTICAL AMPLIFIERS AND LIGHT SOURCE” by Lars Johan Albinsson Nilsson is incorporated herein by reference. This patent describes Single- or few-moded waveguiding cladding-pumped lasers, superfluorescent sources, and amplifiers, as well as lasers, including those for high-energy pulses, in which the interaction between the waveguided light and a gain medium is substantially reduced. This leads to decreased losses of guided desired light as well as to decreased losses through emission of undesired light, compared to devices of the prior art. Furthermore, cross-talk and inter-symbol interference in semiconductor amplifiers can be reduced. Also described are devices with a predetermined saturation power. As a preferred embodiment of the invention, we disclose a single (transverse) mode optical fiber laser or amplifier in which the active medium (providing gain or saturable absorption) is shaped as a ring, situated in a region of the fiber' cross-section where the intensity of the signal light is substantially reduced compared to its peak value. The fiber can be cladding-pumped.
What are needed are improved methods and apparatus for generating high-power pulses of IR and/or green light.